1. Field of the Invention
The present invention relates to an optical transceiver.
2. Related Prior Art
Japanese Patent Application publish as H08-330655 has disclosed a driver circuit for a laser diode (LD) configured with a differential circuit driven by a current source. This LD driver circuit configures one output terminal to a positive power supply via an output bias coil and to the laser diode via a coupling capacitor. This output also connects an impedance circuit in parallel to an antiresonant circuit of a parasitic inductance inherently attributed to the LD and a stray capacitance connected in parallel to the parasitic inductance. This impedance circuit dulls an overshoot and an undershoot that are appeared in the optical output of the LD near the resonant frequency attributed to the parasitic inductance of the LD and the stray capacitance.
Another Japanese Patent Application published as H07-162186 has disclosed an optical transceiver that prevents the interference of the optical transmitting unit with the optical receiving unit, consequently the optical sensitivity from degrading. The optical transceiver includes a multi-layered printed circuit board, an lower case for mounting the multi-layered printed circuit board, and an upper case for enclosing, cooperating with the lower case, the printed circuit board. On the side wall of the lower case is installed with an optical transmitting module and an optical receiving module. The printed circuit board has a first region to install the transmitting circuit and a second region to install the receiving circuit. Between the first and second regions is provided with a first shield plate fixed to the lower case and a second shield plate fixed to the upper case. Accordingly, the crosstalk between the transmitting circuit and the receiving circuit may be reduced.
Still another Japanese Patent Application published as 2000-357803 has disclosed an optical data link. This data link comprises a receptacle, optical transmitting/receiving modules, a plastic package, and a shield case. The shield case prevents a noise radiating from the inside of the data link to the outside and another noise coming from the outside into the data link. Moreover, an existing lead pin realizes the connection to this shield case. This data link, even providing the shield case, does not degrade the optical coupling between the fiber and the light-emitting device or between the fiber and the light-receiving device. This data link provides a cover for the optical transmitting module for shielding which reduces the crosstalk. That is, this data link provides the cover in the transmitting module to protect the receiving module that is intolerant of the noise compared to the optical transmitting unit.
Thus, recent optical data links has a configuration to decrease the noise affecting the optical receiving unit to enhance the receiver sensitivity. In the meantime, the optical transceiver is requested to be small as possible. Therefore, one aspect of the present invention is to provide an optical transceiver capable of reducing the crosstalk induced to the optical receiving unit.